This type of tire is described by way of example in publication No. WO 03/089257 and publication No. JP 2005/186841. This particular construction is designed to improve, among other things, the tire's performance on wet surfaces without reducing its wear and grip qualities on dry surfaces.
The production of this type of tread requires great care in positioning the materials in a precise and reproducible manner. One process has been proposed and published under No. WO 2006/069912. This process involves injecting insertion compounds at predetermined positions into an uncured base tread using a nozzle, after the end of said nozzle has been pushed into said tread. When introducing the green tire into the press, great care is required to line up the resulting inserts with their corresponding tread motifs.
However, it is observed that this process has certain limits, especially when it comes to making precision mouldings. Movements of the rubber during moulding cause random movements of the insertions of compound. This causes considerable dispersion of the interfaces between the compounds, which in turn limits the number of different compounds that can be injected into a tread element.